1. Field of the Invention
The invention generally relates to a coupling mechanism. More specifically, the present invention relates to a coupling mechanism provided with an inertia adding assembly which is interlocked with an input shaft of a transmission to change a vibration system for avoiding resonance and thereby damping a vibration.
2. Background Information
Japanese Patent Publication No. 2-32890 and others have disclosed prior arts relating to a coupling mechanism provided with an inertia adding assembly, which is interlocked with an input shaft of a transmission to change a vibration system of the transmission for damping a vibration.
In these prior art devices, a clutch is engaged when a pressure plate of a clutch cover assembly presses a frictional engagement portion (clutch disk) of a clutch disk assembly against a flywheel of a flywheel assembly, and a sub-clutch (auxiliary clutch) is in the engaged state while the clutch is in the engaged state. In this state, a mass portion (mass member) rotates together with an input shaft of a transmission (i.e., a input shaft of the transmission) so that an additional inertia moment is added to the input shaft of the transmission, and a torque variation of an engine, which is transmitted to the input shaft of the transmission, is reduced. When the clutch is in the disengaged state, the sub-clutch is also in the disengaged state so that the additional inertia moment of the mass portion is not added to the input shaft of the transmission. Therefore, presence of the mass portion does not affect a shift feeling of the transmission.
In the above prior art, the sub-clutch is in the engaged state while the clutch is in the engaged state, and the sub-clutch is in the disengaged state while the clutch is in the disengaged state.
In the above structure of the present invention, however, a large torque is transmitted to the mass portion from the input shaft of the transmission through the sub-clutch when a large torque is transmitted between a crankshaft of the engine and the input shaft of the transmission, e.g., in a starting operation. Therefore, it is necessary to increase the strength of the structures of the sub-clutch and the mass portion for withstanding such a large torque. This increases a weight and a cost of the inertia adding assembly.
In view of the above, there exists a need for a coupling mechanism, which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.